Presents a characteristics-oriented theoretical framework for modal choice by developing a model based conceptually upon Lancaster's "New Approach to Consumer Theory." The model developed contains several constructs that have thus far been overlooked by most travel demand economists: the inclusion of a time constraint; the inclusion of a distance constraint; the modifications of the income constraint to include the money costs of switching modes; and the modification of the time constraint to include the time costs of switching modes. The paper also estimates demand equations suggested by the constraint variables and destinational characteristics defined within the structure of the model. The tests generated extend the application of the abstract modes approach beyond its present use in intercity and interregional transport networks to an international network. The statistical results strongly confirm the appropriateness of such an application, and hence the very general nature of the model. 23 pp. Ref.